The present invention relates generally to a method of producing a terminal for a printed circuit base board wherein the terminal is fixedly connected to the base board by inserting it in a terminal connecting hole and then soldering it to the base board. More particularly, the present invention relates to improvement of a method of the foregoing type wherein soldering connectability to the base board around the periphery of a soldered part is substantially improved.
To facilitate understanding of the present invention, a conventional method of the foregoing type as disclosed in an official gazette of Japanese Patent Laid-Open Publication NO. 58-25091 will be described below with reference to FIG. 4 to FIG. 6. FIG. 4 is a perspective view of a metallic plate and terminals for fixedly securing a connector housing to a printed circuit base board, FIG. 5 is a sectional view of the base board and the connector housing, particularly showing that the connector housing is fixedly mounted on the base board using terminals as shown in FIG. 4, and FIG. 6 is a fragmentary plan view of the base board, particularly showing that a base board connecting portion of the terminal is taken along line A--A in FIG. 5.
Referring to FIG. 4, terminals each generally designated by reference numeral 11 are successively produced by punching a single metallic plate 12 by actuating a press machine (not shown). As shown in FIG. 4, the terminal 11 includes an electrical contact portion 9 having a rectangular sectional shape at the upper part, a base board connecting portion 6 having a rectangular sectional shape at the lower part and a fixing portion 13 at the intermediate part thereof. Referring to FIG. 5, the electrical contact portion 9 is adapted to come in electrical contact with a mating terminal (not shown), the base board connecting portion 6 is connected to a printed circuit base board 3, and the fixing portion 13 is fixedly secured to a connector housing 2. Plated layers 5 previously deposited on the opposite surfaces 12a and 12b of the metallic plate 12 are left alive after completion of each punching operation as they are.
As is apparent from FIG. 5, the terminals 11 are fixedly secured to a bottom wall 13 of the connector housing 2 by press-fitting or integral molding, and the base board connecting portions 6 are connected to the base board 3 by inserting them into terminal connecting holes 4 on the base board 3 and then soldering them to a circuit 14 at 15. As shown in FIG. 6, each terminal connecting hole 4 is formed in the shape of a circular hole in consideration of insertion of the terminal 11 having a rectangular sectional shape without any specific orientation as well as easiness of the formation thereof.
With the conventional terminal 11 constructed in the above-described manner, however, due to the facts that when the base board connecting portion 6 is inserted into the terminal connecting hole 4, a distance (gap) S.sub.1 between one corner of the base board connecting portion 6 and the circuit 12 largely differs from a distance S.sub.2 (gap) between one flat surface of the base board connecting portion 6 and the circuit 14, and moreover, the base board connecting portion 6 is provided with only two plated layers 5 on the opposite surfaces thereof, there arises a problem that the base board connecting portion 6 is connected to the base board 3 by soldering with low connectability, resulting in the electrical connection therebetween being achieved with low reliability. To improve the connectability at the soldered parts, it is thinkable that each of four surfaces of the base board connecting portion 6 is coated with a plated layer 5. In this case, there arises another problem that each terminal 11 is fixedly connected to the base board 3 at an increased cost because of a necessity for subjecting the terminal to plating again.